Phosphatidylethanol Homologues Test

Introduction to PEth

Phosphatidylethanol (PEth) homologues test is a highly sensitive and specific biomarker test that detects direct products of ethanol metabolism in blood, capable of detecting a single drinking episode for up to 12 days and chronic heavy alcohol use for up to 6 weeks 1, 2

PEth testing is now commonly used in the US and Europe to monitor alcohol use in liver transplant centers, with levels directly correlating with the amount of alcohol consumed, making it a semi-quantitative measure of alcohol intake 1, 2
A PEth range of 20–200 ng/ml may indicate alcohol use consistent with MetALD (Metabolic dysfunction and Alcohol-related Liver Disease), which is defined as 20–60 g/day or 140–420 g/week 1, 2
PEth levels >200 ng/ml (typically >500 ng/ml) are consistent with drinking above the MetALD range (>50 g/day in women and >60 g/day in men) 1, 2

PEth has higher specificity compared to indirect markers like GGT, AST, ALT, and MCV, which can be altered by other conditions such as drug ingestion, liver disease, or muscle disease 1, 2, 3
Unlike ethanol testing in blood, breath, or urine, PEth has a much longer detection window 3, 4
PEth is not affected by the presence of compensated or decompensated cirrhosis, unlike some other markers 3, 4

PEth only correlates with recent alcohol use and does not account for historical alcohol use 1, 2, 5
PEth testing should be used as an adjunct to alcohol history taking, standardized questionnaires, and collateral information 1, 2, 5
The applicability of PEth testing may be limited by its cost 1, 2